Tracking the World’s Carbon

Credit: NOAA

Monitoring station at Mauna Loa, Hawaii.

Carbon dioxide, or CO2, is a colorless, odorless gas that’s produced by animals, plants, fungi, and microorganisms by normal respiration. CO2 is used by plants during photosynthesis — the chemical process of converting CO2, sunlight, and water into oxygen. Carbon dioxide also is generated by burning fossil fuels or vegetable matter such as wood from trees. Another minor source can be volcanic eruptions or geothermal processes such as hot springs.

Carbon forms the backbone of organic molecules from which all forms of life that we know are built. Through a process known as the carbon cycle, carbon molecules rotate through the oceans, soils, atmosphere, and living organisms, including plants, animals and humans. The same carbon atoms in your body today have been used in countless other molecules since time began. The wood burned just a few years ago could have produced CO2 that through photosynthesis became part of another plant. When you eat that plant, the same carbon from the wood that was burnt can become part of you. The carbon cycle is the great natural recycler of carbon atoms.

Carbon dioxide and other gases such as water vapor, methane, and nitrous oxide are known as "greenhouse gases". These gases work together to envelope the Earth’s atmosphere trapping the Sun’s radiant heat, similar to the glass of a greenhouse.

Credit: NOAA

Carbon Cycle Diagram.

Using a tool called “CarbonTracker,” NOAA scientists can calculate CO2 emissions to form the ultimate record of combined human and natural influences on greenhouse gas levels. Using this tool will help improve our understanding of how carbon uptake and release from land ecosystems and oceans are responding to a changing climate, the increasing amount of CO2 in the atmosphere, and other environmental changes including human influence.

Credit: NOAA

Carbon Tracker Model.

CO2 measurements are made using an infrared (IR) analyzer consisting of an infrared source at one end, and an infrared detector at the other separated by a gas cell. As the concentration of CO2 changes in the sample, the signal from the detector also changes.

CarbonTracker is a computer modeling system that helps us deduce surface emissions and uptake of CO2 , globally. However, it focuses on North America, where the bulk (65) of the CO2 analyzers are located. CarbonTracker uses sub-models of emissions and uptake of CO2 from fossil fuels, land ecosystems, and the oceans combined with a model of atmospheric winds. This enables us to predict CO2 concentrations that can be compared to measurements. Differences between observed and predicted CO2 are then used to calculate CO2 emissions and uptake.

CarbonTracker will make it possible to accurately track regional emissions over long periods of time and identify emissions that result from fossil fuel use. It also can help identify areas that absorb CO2from the atmosphere that could prove beneficial in offsetting the affect of CO2 emissions. This information will enable NOAA scientists to monitor, diagnose, and possibly predict the behavior of the global carbon cycle and its long-term affect on Earth’s climate.